The invention relates to a hitch mechanism for coupling implements to a utility vehicle.
There are various known hitch or implement coupling mechanisms for coupling an agricultural implement to an agricultural vehicle. One such hitch is the conventional three-point implement hitch, as it is defined by standards ISO 730 or DIN 9674. However, an implement cannot be steered with a conventional three-point hitch. There are guidance mechanisms, such as the Acura Trak from Senco Marketing, which can steer an attached implement, but these mechanisms do not permit a pure lateral shifting of an attached implement. U.S. Pat. No. 5,697,454 shows a mechanism which is pivoted about a vertical pin and which therefore does not permit sideways shifting. Furthermore, there are row guidance mechanisms such as, for example, the "Navigator" from the HR Manufacturing Company, which permit a sideways shifting, but do not provide any implement steering capability.
U.S. Pat. No. 3,432,184 describes a tractor implement hitch which has a triangular plate to which a triangular implement coupling plate can be fastened. Seven variable length actuators extend between the tractor frame and the plate, and have first ends connected to four connecting joints on the tractor frame. Two generally horizontal upper actuators are oriented in a V-shaped pattern with respect to each other and converge with their second ends at an upper joint of the plate. Two generally horizontal lower actuators are oriented parallel to each other and have second ends coupled to lower connecting points on the plate. Two inclined lifting actuators are oriented parallel to each other. They have first ends coupled to the first ends of the upper actuators and have second ends coupled with the second ends of the lower actuators. A lower stabilizing actuator is coupled between the first end of one lower actuator and the second end of the other lower actuator. This hitch is intended to permit rapid and simple attachment of an implements without requiring a precise alignment of the tractor to the implement. The actuators are also used to raise and lower the implement during operation. However, the functions of this hitch are limited. For example, with this hitch an implement cannot be shifted or steered sideways.
"Kinematik und Robotik", by Manfred Husty, Adolf Karger, Hans Sachs, and Waldemar Steinhilper, published in 1997 by x. Springer-Verlag, pages 491-524, describes a mechanism which includes six variable length links coupled between a pair of triangular plates. In this mechanism the links form closed kinematic chains, wherein pairs of the links are connected to a common base or body. A similar mechanism has also been used to support and move a tractor cab in an off-road vehicle simulator, as described by Duncan and Wegscheid in "Off-Road Vehicle Simulation for Human Factors Research", ASAE Paper No. 82-1610 (1982). However, these references do not show such a mechanism in use as a vehicle-implement hitch.